Technical Field
The present disclosure is related to a fixed focus imaging lens for forming optical images of subjects onto an image sensor such as a CCD (Charge Coupled Device) and a CMOS (Complementary Metal Oxide Semiconductor). The present disclosure is also related to an imaging apparatus provided with the imaging lens that performs photography such as a digital still camera, a cellular telephone with a built in camera, a PDA (Personal Digital Assistant), a smart phone, a tablet type terminal, and a portable gaming device.
Description of the Background Art
Accompanying the recent spread of personal computers in households, digital still cameras capable of inputting image data such as photographed scenes and portraits into personal computers are rapidly becoming available. In addition, many cellular telephones, smart phones, and tablet type terminals are being equipped with camera modules for inputting images. Image sensors such as CCD's and CMOS's are employed in these devices having photography functions. Recently, miniaturization of these image sensors is advancing, and there is demand for miniaturization of the entirety of the photography devices as well as imaging lenses to be mounted thereon. At the same time, the number of pixels in image sensors is increasing, and there is demand for high resolution and high performance of imaging lenses. Performance corresponding to 5 megapixels or greater, and more preferably 8 megapixels or greater, is desired.
In response to such demands, imaging lenses having a five or six lens configuration, which is a comparatively large number of lenses, may be considered. For example, Patent Documents 1 and 2 (U.S. Pat. No. 8,000,031 and U.S. Patent Application Publication No. 20120087019) propose an imaging lens with a five-lens configuration, including a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, a fourth lens having a negative refractive power, and a fifth lens having a negative refractive power, disposed in this order from the object side.